The following references are believed to represent the state of the art:
U.S. Pat. No. 6,178,242 to Tsuria;
U.S. Pat. No. 7,305,170 to Okada, et al.;
US Published Patent Application 2005/0122974 of Hubler;
US Published Patent Application 2008/0021937 of Gates, et al.;
US Published Patent Application 2008/0247075 of Holtman;
PCT Published Patent Application WO 2000/01149 of NDS Limited;
PCT Published Patent Application WO 2001/35669 of NDS Limited;
PCT Published Patent Application WO 2003/10970 of NDS Limited; and
An article entitled “Fast Scene Change Detection for Personal Video Recorder” by Jung-Rim King, Sungjoo Suh, and Sanghoon Sull of Korea University, June 2003, IEEE.